The email purportedly sent by outlawed Indian Mujahideen owning up the attacks outside Jama Masjid and threatening more strikes ahead of Commonwealth Games has been traced to Borivali area of Mumbai, police said on Tuesday.
The mail was sent using a Tata phone connection procured through a fake identity card.
One person is understood to have been questioned by Delhi Police in this regard. Police suspect the person has some link to the firing incident.
The Indian Mujahideen had in an email sent to various media houses threatened to unleash violence during the Commonwealth Games soon after Sunday's firing incident at the Jama Masjid in which two Taiwanese nationals were injured.
An e-mail sent to BBC does not directly refer to the incident of firing but says, "in the name of Allah, the attack is a tribute to Atif Amin and Mohammed Sajid."
Both of them were killed by the police in the Batla House encounter on September 19, 2008.
"We are warning you. If you have the guts, then organise the Commonwealth Games...We know that preparations are on full swing. Be prepared...We are also making preparations...The participants in the games will be responsible for the outcome," the mail said.
The statement also denounced the killings of civilians in the Kashmir Valley.